Abstract
An experiment was conducted to determine if changes in the level of dietary amino acids fed to laying hens as a single amino acid or a natural protein reflected on changes in plasma amino acid content.
A basal diet was formulated in which all essential amino acids were not less than NRC requirements. A high-protein diet was made with the addition of 10% fish meal to the basal diet, and a high-valine diet was made by the addition of 0.3% valine to the basal diet.
The concentrations of eight plasma amino acids (threonine, valine, methionine and cystine, isoleucine, leucine, lysine, and arginine) increased within 7 days and thereafter remained constant on the high-protein diet. But those of five amino acids (serine, glutamic acid, alanine, tyrosine, and phenylalanine) were kept constant throughout the experiment. On the valine diet, the concentration of plasma valine increased until 14 days, but those of other amino acids remained constant.
The data suggests that plasma amino acids levels may serve as a more effective and rapid evaluation of changes in dietary status than a long term feeding test.
